Ferguson celebrates two decades at the helm on Monday - and must be extremely satisfied with the calibre and form of his current crop of players.

United have not lost in the Premiership since defeat by Arsenal on 17 September, though Chelsea can pull level on points with them at the top of the table if they beat Tottenham at White Hart Lane on Sunday.

The home team eased to victory and if Ferguson's men could be faulted it was that they should have scored more goals, though Pompey keeper James made a series of excellent saves.

The match was effectively over as a contest when Ronaldo scored United's second goal after 10 minutes.

Saha had already put United ahead, his penalty just eluding James' valiant dive, before Ronaldo made the most of Ryan Giggs' intelligent play.

The Wales winger lined up at the edge of the Pompey wall after a free-kick had been awarded for a poor tackle on Saha by Andy O'Brien.

Giggs peeled away as Ronaldo approached the ball and the Portugal star smashed his free-kick through the gap and into the net.

United, with such a commanding advantage so early in the match, launched attack after attack upon their bewildered opponents.

Neville twice came close to a rare goal for United in the first half but each time was thwarted by James saving with his legs.

James was having an extremely busy afternoon and after his block broke to Paul Scholes he had team-mate O'Brien to thank for heading the United midfielder's shot clear of goal.

Rooney was in fine form; the catalyst for numerous United attacks with his precise, clever kicks and forceful dribbling.

Pompey, in stark contrast, mustered nothing of worth until the stroke of half-time when Edwin van der Sar made a superb save to keep out Matthew Taylor's thunderous long-range strike.

Rooney almost scored straight after the restart with a low strike from distance - while at the other end Kranjcar wasted an excellent chance, missing the target after the ball broke to him in space 12 yards from goal.

United continued to press and Rooney shot wide under pressure following a mazy run before Vidic added a third from Neville's cross.

James made further saves from Neville and Saha, while substitute Darren Fletcher shot wide.